Alignment bushing for needle valve



P 30, 1969 c. DU BOIS 3,469,825

ALIGNMENT BUSHING FOR NEEDLE VALVE Filed Oct. 12, 1967 V w V /o) 1 v 4l2 20 a2 22 24 27 /9 Z9 Z5 F INVIN'T'QZ 674:3 r-Ee Du 50 5 ATTORN UnitedStates Patent 3,469,825 ALIGNMENT BUSHING FOR NEEDLE VALVE ChesterDuBois, Zion, Ill., assignor to Outboard Marine Corporation, Waukegan,11]., a corporation of Delaware Filed Oct. 12, 1967, Ser. No. 674,854Int. Cl. F02m 19/04, 19/06 US. Cl. 261-71 4 Claims ABSTRACT OF THEDISCLOSURE Disclosed herein is a resilient alignment bushing for theneedle valve of a carburetor. The bushing comprises concentric inner andouter surfaces with the inner surface defining an axial aperture whichreceives the needle valve and maintains the valve member in concentricrelation to the valve seat. The outer surface of the bushing engages thebore in the carburetor housing to afford a fluid seal.

BACKGROUND OF INVENTION The invention relates to needle valves used toadjust fluid flow in carburetors and more particularly to an alignmentbushing for such needle valves. The accepted manufacturing tolerancesobserved in carburetor construction are such that vibratory movementbetween the needle point and the needle seat is possible as a result ofnormal engine vibrations. Such vibratory movement can result ininterference with consistent metering of the fluid flow through thevalve and wear of the needle portion and valve seat.

SUMMARY OF INVENTION The invention provides an alignment bushing for aneedle valve of a carburetor to minimize vibratory movement between theneedle valve and the needle seat and to minimize wear of the needleportion and seat. The bushing of the invention has concentric inner andouter surfaces with the outer surface engaging the bore in the valvehousing in which the valve body is located and the inner surfaceengaging the needle valve member. The concentric relationship betweenthe inner and outer surfaces is maintained by a nondeformable barrierbetween the wall portions providing such outer and inner surfaces. Thefit of the bushing and the valve bore and valve member also affords afluid seal between the bore and the fluid passage and axial movement ofthe valve member within the bore. The alignment bushing is desirablyconstructed of a resilient material such as nylon.

The object of this invention is to provide a device that will reduce thevibratory movement to an acceptable minimum by maintaining theconcentricity between the needle point and the seat yet allowmanufacturing tolerances that are economical to produce.

Another object of this invention is to improve the metering consistencyby maintaining a more stable relationship between the needle point andthe needle seat which will then be substantially immune to the adverseeffects of vibration. Another object is to provide an effective sealagainst leakage to the atmosphere between the needle valve threads andthe fuel passage.

Further objects and advantages of the invention will become apparentfrom the following disclosure.

DRAWINGS FIGURE 1 is an enlarged vertical sectional view of a carburetorembodying the present invention.

FIGURE 2 is an enlarged sectional view of the alignment bushing shown inFIGURE 1.

FIGURE 3 is a partially broken away perspective view of the alignmentbushing shown in FIGURE 1.

DETAILED DESCRIPTION In the drawings there is shown a carburetor whichis generally designated 10 and which includes a carburetor body orhousing 12, a mixing chamber 14, a float chamber 16 and a fluid passage18 connecting the float chamber 16 with the mixing chamber 14. Flow offluid through the fluid passage 18 from the float valve to the mixingchamber is controlled or metered by a valve 19 which includes a valvebody 20 located in a bore 21 defined by the wall 23 of the bore 21 inthe carburetor housing 12. The bore 21 communicates with the fluidpassage 18.

The valve body 20 has a valve member or needle portion 22 which includesa tip and shank, the tip being located for cooperation with a restrictedportion in the fluid passage 18, which portion forms a valve seat 24.Adjustment of the valve body axially is aflorded by a threaded portion25 of the valve body located at one end of the valve body stem 26. Thethreaded portion is received in a threaded bore of a nut 27. A gasket 29is conventionally provided to maintain a seal.

The invention contemplates the reduction of wear of the needle portion22 and the valve seat 24 caused by vibratory movement of the needleportion as a result of engine vibration, thus aifording consistentmetering 0f flow through the fluid passage 18. In this regard, means areprovided for maintaining the valve needle portion 22 in concentricrelation to and centered within the valve seat 24 to minimize contactcaused by vibratory move ment. In the construction disclosed in FIGURES1 through 3 the means comprises a bushing 32 which is desirablyconstructed of a resilient material such as nylon and is in the form ofa large frustoconical wall portion 33 and a small frustoconical wallportion 34 with an outside diameter less than the outside diameter ofthe first wall portion. The wall portion 34 is located at one end of thewall portion 33 and in concentric relation therewith. The wall portions33, 34 are connected at juncture 35 and define an axial aperture 36through which the valve body 20 extends.

The juncture 35 between the wall portions 33 and 34 is equal inthickness to the combined thickness of each of the wall portions 33 and34 and forms a nondeformable barrier which serves to maintain theconcentric relationship between surfaces 37 and 38 notwithstandingradial compression of wall portion 33 as it is inserted in bore 21 orradial expansion of wall portion 34 when the needle portion 22 isextended through the bushing 32. Thus, the fit of the Wall portion 34with the shank of the needle portion 22 is independent of the fit of thewall portion 33 with the wall of the bore 21.

A fluid seal between the fluid passage 18 and the bore 21 is afforded'by the fit between surface 37 and bore wall 23 and the shaft sealbetween the shank of needle portion 22 and the surface 38.

The frustoconical shape of the bushing shown in FIG- URES 1 through 3facilitates insertion of the bushing in the valve chamber and preventsmovement of the bushing 32 relative to the bore 21.

FIGURE 4 shows a modified embodiment of the invention. In thisembodiment the means for maintaining concentricity of the needle valvemember 22 with respect to the seat 24 is in the form of a bushing 40having a frustoconical outer wall 42 which tapers inwardly toward thevalve seat and an inverted frustoconical inner wall 44 which tapersinwardly toward the valve body 20. The

Patented Sept. 30, 1969 juncture 45 between wall portion 42 and wallportion 44 is at the end of the bushing adjacent the fluid passage 18.The outer surface 46 of the wall portion 42 engages the wall 23 of thebore 21 and the inner surface 47 of the wall 44 engages the shank of theneedle portion 22. The wall portions 42 and 44 are in concentricrelation and maintain such relation when compressed upon insertion inthe valve bore 21.

A further embodiment of the invention is illustrated in FIGURE 5. Inthis embodiment the alignment :bushing comprises an annulus or O-ring 48which has an outer surface 49 in engagement with the bore wall 23 and aninner surface 50 in engagement with the needle portion 22.

Although several embodiments of the invention are disclosed herein, theuse in connection with a carburetor needle valve of any resilientbushing which can maintain the concentrieity of its inner and outerwalls upon being slightly compressed and seal the fluid assage from thebore is within the purview of the invention.

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:

1. In a carburetor having a housing with a mixing chamber, a fluidpassage having a valve seat in said housing, said fluid passageconnecting a fluid source with said mixing chamber, a bore in saidhousing communicating with said fluid passage, and a valve memberadjustably movable axially within said bore for cooperation of saidvalve member with said valve seat to meter fluid flow through said fluidpassage into said carburetor mixing chamber, the improvement comprisinga bushing having a frustoconical wall portion with an outer surfaceengaging said bore, a second frustoconical wall portion at one end ofsaid first wall portion and in concentric relation to said first wallportion and having an outside diameter less than said firstfrustoconical portion, said first and second wall portions having innersurfaces defining an axial aperture, said valve member extending throughsaid axial aperture, and said inner surface of said second wall portionengaging said valve member.

2. The improvement of claim 1 wherein said first and second fmstoconicalwall portions are joined by a juncture which is thicker than each ofsaid wall portions to aflord a barrier against deformation of saidsecond portion upon compression of said first portion.

3. A carburetor comprising a housing having a mixing chamber, a fluidpassage in said housing communicating with said mixing chamber, saidfluid passage having a restriction forming a valve seat, a bore in saidhousing communicating with said fluid passage and concentric to saidvalve seat, a valve body in said bore with a valve member movableaxially within said bore and said fluid passage to cooperate with saidvalve seat to meter flow through said fluid passage, a bushing in saidbore, said bushing having a frustoconcial outer wall portion taperingtoward said valve member, and a frustoconical inner wall portionconcentric to said outer wall portion and connected thereto at the endof said outer wall portion adjacent said valve member, said inner wallportion tapering toward said valve member in the direction converse tosaid direction of taper of said outer wall portion to define an axialaperture which receives said valve member and interfits therewith toafford axial movement of said valve member and a fluid seal between saidfluid passage and said bore,

4. A carburetor in accordance with claim 3 wherein said inner and outerconcentric wall portions are connected by a nondeformable barrier.

References Cited UNITED STATES PATENTS 2,840,359 6/ 1958 Cornelius.

2,841,429 7/ 1958 McCuistion.

2,918,973 12/1959 Ozinga 277-212 X 2,970,649 2/1961 Brown 277-212 X3,125,084 3/1964 Hall 261-69 X 3,126,795 3/ 1964 Kesselring.

3,157,170 11/1964 Reid.

3,192,942 7/1965 Manor et al 251-214 X 3,231,250 1/1966 Kalert 261-71 X3,240,230 3/1966 Callahan et a1. 251-214 3,330,545 7/1967 Donovan.

TIM R. MILES, Primary Examiner US. Cl. X.R. 251-214; 277-212

